Tissue-removing catheter

ABSTRACT

A tissue-removing catheter for removing tissue in a body lumen includes an elongate body. A tissue-removing element mounted on a distal end portion of the elongate body. The tissue-removing element includes a body including an exterior surface having a first segment extending from a proximal end toward a distal end of the tissue-removing element. A second segment extends from the first segment toward the distal end of the tissue-removing element. A third segment extends from the second segment to the distal end of the tissue-removing element. A transition between the first and second segments defines a first angle formed between the first and second segments. A transition between the second and third segments defines a second angle formed between the second and third segments. The tissue-removing element is configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of, and priority to, U.S.Provisional Application Ser. No. 62/500,867, which was filed May 3,2017, and U.S. Patent Application Ser. No. 62/500,879, which was filedMay 3, 2017, each of which is incorporated herein by reference in itsentirety for all purposes.

FIELD

The present disclosure generally relates to a tissue-removing catheter,and more particular, to a tissue-removing element for a tissue-removingcatheter.

BACKGROUND

Tissue-removing catheters are used to remove unwanted tissue in bodylumens. As an example, atherectomy catheters are used to remove materialfrom a blood vessel to open the blood vessel and improve blood flowthrough the vessel. This process can be used to prepare lesions within apatient's coronary artery to facilitate percutaneous coronaryangioplasty (PTCA) or stent delivery in patients with severely calcifiedcoronary artery lesions. Atherectomy catheters typically employ arotating element which is used to abrade or otherwise break up theunwanted tissue.

SUMMARY

In one aspect, a tissue-removing catheter for removing tissue in a bodylumen generally comprises an elongate body having an axis and proximaland distal end portions spaced apart from one another along the axis.The elongate body is sized and shaped to be received in the body lumen.A tissue-removing element is mounted on the distal end portion of theelongate body. The tissue-removing element comprises a body including anexterior surface having a first segment extending from a proximal endtoward a distal end of the tissue-removing element, a second segmentextending from the first segment toward the distal end of thetissue-removing element, and a third segment extending from the secondsegment to the distal end of the tissue-removing element. A transitionbetween the first and second segments defines a first angle formedbetween the first and second segments. A transition between the secondand third segments defines a second angle formed between the second andthird segments. The tissue-removing element is configured to remove thetissue as the tissue-removing element is rotated by the elongate bodywithin the body lumen.

In another aspect, a tissue-removing element for use with a tissueremoving catheter for removing tissue in a body lumen generallycomprises a body including an exterior surface having a first segmentextending from a proximal end toward a distal end of the tissue-removingelement. A second segment extends from the first segment toward thedistal end of the tissue-removing element. A third segment extends fromthe second segment to the distal end of the tissue-removing element. Atransition between the first and second segments defines a first angleformed between the first and second segments. A transition between thesecond and third segments defines a second angle formed between thesecond and third segments. The tissue-removing element is configured toremove the tissue as the tissue-removing element is rotated by thetissue-removing catheter within the body lumen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation of a catheter of the present disclosure;

FIG. 2 is an enlarged elevation of a distal end portion of the catheter;

FIG. 3 is an enlarged elevation of a proximal end portion of thecatheter;

FIG. 4 is an enlarged fragmentary longitudinal cross section of thedistal end portion of the catheter in FIG. 2;

FIG. 5 is a cross section taken through line 5-5 in FIG. 2;

FIG. 6 is a fragmentary elevation of an isolation liner of the catheterwith portions broken away to show internal details;

FIG. 7 is an enlarged elevation of a distal end portion of the cathetershowing an atraumatic tip on an inner liner;

FIG. 8 is an enlarged elevation of a distal end portion of the cathetershowing a tapered tip on the inner liner; and

FIG. 9 is an enlarged longitudinal cross section of a tissue-removingelement of the catheter.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION

Referring to the drawings, and in particular FIG. 1, a rotationaltissue-removing catheter for removing tissue in a body lumen isgenerally indicated at reference number 10. The illustrated catheter 10is a rotational atherectomy device suitable for removing (e.g.,abrading, cutting, excising, ablating, etc.) occlusive tissue (e.g.,embolic tissue, plaque tissue, atheroma, thrombolytic tissue, stenotictissue, hyperplastic tissue, neoplastic tissue, etc.) from a vessel wall(e.g., coronary arterial wall, etc.). The catheter 10 may be used tofacilitate percutaneous coronary angioplasty (PTCA) or the subsequentdelivery of a stent. Features of the disclosed embodiments may also besuitable for treating chronic total occlusion (CTO) of blood vessels,and stenoses of other body lumens and other hyperplastic and neoplasticconditions in other body lumens, such as the ureter, the biliary duct,respiratory passages, the pancreatic duct, the lymphatic duct, and thelike. Neoplastic cell growth will often occur as a result of a tumorsurrounding and intruding into a body lumen. Removal of such materialcan thus be beneficial to maintain patency of the body lumen.

The catheter 10 is sized for being received in a blood vessel of asubject. Thus, the catheter 10 may have a maximum size of 3, 4, 5, 6, 7,8, 9, 10, or 12 French (1, 1.3, 1.7, 2, 2.3, 2.7, 3, 3.3, or 4 mm) andmay have a working length of 20, 30, 40, 60, 80, 100, 120, 150, 180 or210 cm depending of the body lumen. While the remaining discussion isdirected toward a catheter for removing tissue in blood vessels, it willbe appreciated that the teachings of the present disclosure also applyto other types of tissue-removing catheters, including, but not limitedto, catheters for penetrating and/or removing tissue from a variety ofocclusive, stenotic, or hyperplastic material in a variety of bodylumens.

Referring to FIGS. 1 and 2, the catheter 10 comprises an elongate outerlayer 12 (broadly, an elongate body) disposed around an elongate innerliner 14. The outer layer 12 and inner liner 14 extend along alongitudinal axis LA of the catheter from a proximal end portion 16 to adistal end portion 18 of the catheter. A tissue-removing element 20 isdisposed on a distal end of the outer layer 12 and is configured forrotation to remove tissue from a body lumen as will be explained ingreater detail below. A sheath 22 (FIG. 1) is disposed around the outerlayer 12. The outer layer 12 and the inner liner 14 are both configuredto translate relative to the sheath 22. The outer layer 12 and innerliner 14 are also configured to translate relative to each other. Thecatheter 10 is sized and shaped for insertion into a body lumen of asubject. The sheath 22 isolates the body lumen from at least a portionof the outer layer 12 and inner liner 14. The inner liner 14 defines aguidewire lumen 24 (FIG. 5) for slidably receiving a guidewire 26therein so that the catheter 10 can be advanced through the body lumenby traveling along the guidewire. The guidewire 26 can be a standard0.014 inch outer diameter, 300 cm length guidewire. In certainembodiments, the inner liner 14 may have a lubricious inner surface forsliding over the guidewire 26 (e.g., a lubricious surface may beprovided by a lubricious polymer layer or a lubricious coating). In theillustrated embodiment, the guidewire lumen 24 extends from the proximalend portion 16 through the distal end portion 18 of the catheter 10 suchthat the guidewire 26 is extendable along an entire working length ofthe catheter 10. In one embodiment, the overall working length of thecatheter 10 may be between about 135 cm (53 inches) and about 142 cm (56inches).

The catheter 10 further comprises a handle 40 secured at the proximalend portion 16 of the catheter. The handle 40 supports an actuator 42(e.g., a lever, a button, a dial, a switch, or other device) configuredfor selectively actuating a motor 43 disposed in the handle to driverotation of the outer layer 12, and tissue-removing element 20 mountedat the distal end of the outer layer. The motor 43 is coupled to theouter layer 12 by a gear assembly 44 and drive 48 supported by thehandle 40. A slide or advancer 45 is positioned on the handle 40 andoperatively coupled to the outer layer 12 for movement of the outerlayer relative to the handle to advance and retract the outer layer andtissue-removing element 20. The handle 40 defines a slot (not shown)which limits the movement of the slide 45 relative to the handle. Thus,the length of the slot determines the amount of relative movementbetween the outer layer 12 and the handle 40. A perfusion port 46 may bedisposed at the proximal end 16 of the catheter 10. The port 46communicates with a space between the sheath 22 and the outer layer 12for delivering fluid (e.g., saline) to cool the rotating outer layerduring use. A proximal port 47 allows for passage of the guidewire 26and inner liner 14 through the proximal end of the handle 40. Aguidewire lock (not shown) may be provided on the handle 40 to lock theguidewire 26 in place relative to the handle.

It is understood that other suitable actuators, including but notlimited to touchscreen actuators, wireless control actuators, automatedactuators directed by a controller, etc., may be suitable to selectivelyactuate the motor in other embodiments. In some embodiments, a powersupply may come from a battery (not shown) contained within the handle40. In other embodiments, the power supply may come from an externalsource.

Referring to FIGS. 1 and 3, the outer sheath 22 comprises a tubularsleeve configured to isolate and protect a subject's arterial tissuewithin a body lumen from the rotating outer layer 12. The sheath 22 isfixed to the handle 40 at a proximal end of the sheath and does notrotate. A hub 52 mounted on the proximal end of the sheath 22 attachesthe sheath to the handle 40. The hub 52 includes a locking feature 54(e.g., threaded luer lock) for engaging the handle 40 to attach thesheath 22 to the handle. The sheath 22 provides a partial enclosure forthe outer layer 12 and inner liner 14 to move within the sheath. Theinner diameter of the sheath 22 is sized to provide clearance for theouter layer 12. The space between the sheath 22 and the outer layer 12allows for the outer layer to rotate within the sheath and provides anarea for saline perfusion between the sheath and outer layer. The outerdiameter of the sheath 22 is sized to provide clearance with an innerdiameter of a guide catheter (not shown) for delivering the catheter 10to the desired location in the body lumen. A strain relief 56 isprovided at the proximal end of the sheath 22 to alleviate tensionapplied to the proximal end of the sheath 22 as the sheath is bentduring use of the catheter 10. In one embodiment, the sheath 22 has aninner diameter of about 0.050 inches (1.27 mm), an outer diameter ofabout 0.055 inches (1.4 mm), and a length of about 1500 mm (59 inches).The sheath 22 can have other dimensions without departing from the scopeof the disclosure. In one embodiment, the outer sheath 22 is made fromPolytetrafluorethylene (PTFE). Alternatively, the outer sheath 22 maycomprise a multi-layer construction. For example, the outer sheath 22may comprises an inner layer of perfluoroalkox (PFA), a middle braidedwire layer, and an outer layer of Pebax.

Referring to FIGS. 1, 2, 4, and 5, the outer layer 12 may comprise atubular stainless steel coil configured to transfer rotation and torquefrom the motor 43 to the tissue-removing element 20. Configuring theouter layer 12 as a coiled structure provides the outer layer with aflexibility that facilitates delivery of the catheter 10 through thebody lumen. Also, the coil configuration allows for the rotation andtorque of the outer layer 12 to be applied to the tissue-removingelement 20 when the catheter 10 is traversed across a curved path. Thestiffness of the outer layer 12 also impacts the ease at which the coilis traversed through the body lumen as well as the coil's ability toeffectively transfer torque to the tissue-removing element 20. In oneembodiment, the outer layer 12 is relatively stiff such that axialcompression and extension of the coil is minimized during movement ofthe catheter 10 through a body lumen. The coil configuration of theouter layer 12 is also configured to expand its inner diameter when thecoil is rotated so that the outer layer remains spaced from the innerliner 14 during operation of the catheter 10. In one embodiment, theouter layer 12 has an inner diameter of about 0.023 inches (0.6 mm) andan outer diameter of about 0.035 inches (0.9 mm). The outer layer 12 mayhave a single layer construction. For example, the outer layer maycomprise a 7 filar (i.e., wire) coil with a lay angle of about 30degrees. Alternatively, the outer layer 12 could be configured frommultiple layers without departing from the scope of the disclosure. Forexample, the outer layer 12 may comprise a base coil layer and a jacket(e.g., Tecothane™) disposed over the base layer. In one embodiment, theouter layer comprises a 15 filar coil with a lay angle of about 45degrees. The Tecothane™ jacket may be disposed over the coil.Alternatively, the outer layer 12 may comprise a dual coil layerconfiguration which also includes an additional jacket layer over thetwo coil layers. For example, the outer layer may comprise an inner coillayer comprising a 15 filar coil with a lay angle of about 45 degrees,and an outer coil layer comprising a 19 filar coil with a lay angle ofabout 10 degrees. Outer layers having other configurations are alsoenvisioned.

Referring to FIGS. 1, 2, and 4-6, the inner liner 14 comprises amultiple layer tubular body configured to isolate the guidewire 26 fromthe outer layer 12 and tissue-removing element 20. The inner liner 14 isextendable through the handle 40 from a position proximal of the handleto a position distal of the handle. In one embodiment, the inner liner14 is coupled to the handle 40 but is not fixedly attached to the handle40 to allow translation of the inner liner relative to the handle. Inthis embodiment, rotation of the inner liner 14 is not prevented.However, the clearance between the inner liner 14 and the outer layer 12prevents any rotation of the inner liner caused by the rotation of theouter layer. In this embodiment, both the inner liner 14 and outer layer12 are permitted to translate relative to the handle 40. Allowing thisco-translation of the inner liner 14 and outer layer 12 minimizescompression and extension of the coiled outer layer 14 when force isapplied to the outer layer to move the outer layer within the bodylumen. In another embodiment, the inner liner 14 may be fixedly attachedto the handle 40 to prevent relative movement between the inner linerand the handle. Thus, in this embodiment, the inner liner 14 remainsstationary and is prevented from translating relative to the handle 40.Additionally, all rotation of the inner liner 14 is prevented. In thisembodiment, the outer layer 12 translates over the stationary innerliner 14.

The inner liner 14 has an inner diameter that is sized to pass theguidewire 26. The inner liner 14 protects the guide wire from beingdamaged by the rotation of the outer layer 12 by isolating the guidewirefrom the rotatable outer layer. The inner liner 14 also extends past thetissue-removing element 20 to protect the guidewire 26 from the rotatingtissue-removing element. Thus, the inner liner 14 is configured toprevent any contact between the guidewire 26 and the rotating componentsof the catheter 10. Therefore, any metal-to-metal engagement iseliminated by the inner liner 14. This isolation of the outer layer 12and tissue-removing element 20 from the guidewire 26 also ensures thatthe rotation of the outer layer and tissue-removing element is nottransferred or transmitted to the guidewire. As a result, a standardguidewire 26 can be used with the catheter 10 because the guidewire doesnot have to be configured to withstand the torsional effects of therotating components. Additionally, by extending through thetissue-removing element 20 and past the distal end of thetissue-removing element, the inner liner 14 stabilizes thetissue-removing element by providing a centering axis for rotation ofthe tissue-removing element about the inner liner.

In the illustrated embodiment, the inner liner 14 comprises an innerPTFE layer 60, an intermediate braided layer 62 comprised of stainlesssteel, and an outer layer 64 of polyimide. The PTFE inner layer 60provides the inner liner 14 with a lubricous interior which aids in thepassing of the guidewire 26 though the inner liner. The braidedstainless steel intermediate layer 62 provides rigidity and strength tothe inner liner 14 so that the liner can withstand the torsional forcesexerted on the inner liner by the outer layer 12. In one embodiment, theintermediate layer 62 is formed from 304 stainless steel. The outerpolyimide layer 64 provides wear resistance as well as having alubricous quality which reduces friction between the inner liner 14 andthe outer layer 12. In one embodiment, the inner liner 14 has an innerdiameter ID of about 0.016 inches (0.4 mm), an outer diameter OD ofabout 0.019 inches (0.5 mm), and a length of about 59 inches (1500 mm).The inner diameter ID of the inner liner 14 provide clearance for thestandard 0.014 inch guidewire 26. The outer diameter OD of the innerliner 14 provides clearance for the outer layer 12 and tissue-removingelement 20. Having a space between the inner liner 14 and the outerlayer 12 reduces friction between the two components as well as allowsfor saline perfusion between the components.

In the illustrated embodiment, a marker band 66 is provided on anexterior surface of the distal end of the inner liner 14. The markerband 66 configures the tip of the inner liner 14 to be fluoroscopicallyvisible which allow a physician to verify the position of the linerduring a medical procedure. In this embodiment, the distal end of theinner liner 14 may be laser cut to provide a low profile tip. In oneembodiment, the marker band 66 comprises a strip of platinum iridium.

It is further envisioned that the distal end of the inner liner 14 canhave other constructions without departing from the scope of thedisclosure. For example, an atraumatic tip 68 may be attached to thedistal end of the inner liner 14 (FIG. 7). The atraumatic tip 68provides a soft, low profile distal end to facilitate delivery of theinner liner 14 through the body lumen without causing trauma. Theatraumatic tip 68 may have a maximum outer diameter of about 0.02 inches(0.6 mm). Other sizes of the atraumatic tip are also envisioned. Inanother embodiment, a tapered tip 70 may be attached to the distal endof the inner liner 14 (FIG. 8). The tapered tip 70 may be formed from alayer of material configured to protect the distal end of the innerliner 14.

Referring to FIGS. 1, 2, and 9, the tissue-removing element 20 comprisesa body extending along a longitudinal axis LA2 from a proximal endadjacent the distal end portion of the outer layer 12 to an oppositedistal end. The tissue-removing element 20 is operatively connected tothe motor 43 for being rotated by the motor. When the catheter 10 isinserted into the body lumen and the motor 43 is rotating thetissue-removing element 20, the tissue-removing element is configured toremove occlusive tissue in the body lumen to separate the tissue fromthe wall of the body lumen. Any suitable tissue-removing element forremoving tissue in the body lumen as it is rotated may be used in one ormore embodiments. In one embodiment, the tissue-removing element 20comprises an abrasive burr configured to abrade tissue in the body lumenwhen the motor 43 rotates the abrasive burr. The abrasive burr 20 mayhave an abrasive outer surface formed, for example, by a diamond gritcoating, surface etching, or the like. In one embodiment, thetissue-removing element 20 comprises a stainless steel spheroid bodywith an exterior surface including between about 2 and about 50 μm ofexposed diamond crystals. In one embodiment, the tissue-removing element20 includes about 5 μm of exposed diamond crystals. The tissue-removingelement 20 may also be made from titanium, brass, or ceramic such aszirconia. Other materials are also envisioned. The tissue-removingelement 20 may also be radiopaque to allow the tissue-removing elementto be visible under fluoroscopy. In other embodiments, thetissue-removing element can comprise one or more cutting elements havingsmooth or serrated cutting edges, a macerator, a thrombectomy wire, etc.

A cavity 72 extends longitudinally through the body of thetissue-removing element 20 such that the tissue-removing element definesopenings at its proximal and distal ends. The cavity 72 receives aportion of the outer layer 12 for mounting the tissue-removing element20 to the outer layer. The cavity 72 includes a first diameter portion74 extending from the proximal end of the tissue-removing element 20, atapered diameter portion 76 extending from the first diameter portiontoward the distal end of the tissue-removing element, and a seconddiameter portion 78 extending from the tapered diameter portion to thedistal end of the tissue-removing element. The diameters of the firstand second diameter portions 74, 78 are constant along their lengths. Inthe illustrated embodiment, a diameter D1 of the first diameter portion74 is larger than a diameter D2 of the second diameter portion 78. Inone embodiment, the diameter D1 of the first diameter portion 74 isabout 0.035 inches (0.9 mm), and the diameter D2 of the second diameterportion 78 is about 0.022 inches (0.56 mm). The tapered diameter portion76 provides a transition between the first and second diameter portions74, 78. The outer layer 12 is received in the first diameter portion 74and a distal end of the outer layer abuts the tapered diameter portion76. The tissue-removing element 20 can be fixedly attached to the distalend of the outer layer 12 by any suitable means. In one embodiment anadhesive bonds the tissue-removing element 20 to the outer layer 12. Theinner liner 14 extends through the outer layer 12 and the seconddiameter portion 78 of the tissue-removing element 20. The seconddiameter portion 78 is sized to pass the inner liner 14 with a smallclearance. The inner diameter D2 provides clearance between thetissue-removing element 20 and inner liner 14 to reduce friction betweenthe components and allow a space for saline perfusion. Accordingly, thetissue-removing element 20 is shaped and arranged to extend around atleast a portion of the outer layer 12 and inner liner 14 and thusprovides a relatively compact assembly for abrading tissue at the distalend portion of the catheter 10.

The exterior surface of the body of the tissue-removing element 20includes a proximal segment 80, a middle segment 82, and a distalsegment 84. A diameter of the proximal segment 80 increases from theproximal end of the tissue-removing element 20 to the middle segment 82.The middle segment has a constant diameter and extends from the proximalsegment 80 to the distal segment 84. The diameter of the distal segment84 tapers from the middle segment 82 to the distal end of thetissue-removing element 20. A transition between the proximal segment 80and the middle segment 82 forms a first angle α between the proximal andmiddle segments. In one embodiment, the angle α is less than about 170degrees. In one embodiment, the angle α is about 165 degrees. Similarly,a transition between the middle segment 82 and the distal segment 84forms a second angle β between the middle and distal segments. In oneembodiment, the angle β is less than about 170 degrees. In oneembodiment, the angle β is about 165 degrees. The tapered proximal anddistal segments 80, 84 provide the tissue-removing element 20 with ageneral front and back wedge shaped configuration for wedging apartconstricted tissue passages as it simultaneously opens the passage byremoving tissue using the abrasive action of the tissue-removingelement. The distal end of the tissue-removing element 20 is alsorounded to provide the tissue-removing element with a blunt distal end.

Referring to FIGS. 1 and 2, to remove tissue in the body lumen of asubject, a practitioner inserts the guidewire 26 into the body lumen ofthe subject, to a location distal of the tissue that is to be removed.Subsequently, the practitioner inserts the proximal end portion of theguidewire 26 through the guidewire lumen 24 of the inner liner 14 andthrough the handle 40 so that the guidewire extends through the proximalport 47 in the handle. The inner liner 14 may also extend through thehandle 40 and out the proximal port 47. With the catheter 10 loaded ontothe guidewire 26, the practitioner advances the catheter along theguidewire until the tissue-removing element 20 is positioned proximaland adjacent the tissue. When the tissue-removing element 20 ispositioned proximal and adjacent the tissue, the practitioner actuatesthe motor 43 using the actuator 42 to rotate the outer layer 12 and thetissue-removing element mounted on the outer layer. The tissue-removingelement 20 abrades (or otherwise removes) the tissue in the body lumenas it rotates. While the tissue-removing element 20 is rotating, thepractitioner may selectively move the outer layer 12 and inner liner 14distally along the guidewire 26 to abrade the tissue and, for example,increase the size of the passage through the body lumen. Thepractitioner may also move the outer layer 12 and inner liner 14proximally along the guidewire 26, and may repetitively move thecomponents in distal and proximal directions to obtain a back-and-forthmotion of the tissue-removing element 20 across the tissue. During theabrading process, the inner liner 14 isolates the guidewire 26 from therotating outer layer 12 and tissue-removing element 20 to protect theguidewire from being damaged by the rotating components. As such, theinner liner 14 is configured to withstand the torsional and frictionaleffects of the rotating outer layer 12 and tissue-removing element 20without transferring those effects to the guidewire 26. When thepractitioner is finished using the catheter 10, the catheter can bewithdrawn from the body lumen and unloaded from the guidewire 26 bysliding the catheter proximally along the guidewire. The guidewire 26used for the abrading process may remain in the body lumen for use in asubsequent procedure.

When introducing elements of the present invention or the one or moreembodiment(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above apparatuses, systems, andmethods without departing from the scope of the invention, it isintended that all matter contained in the above description and shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:
 1. A tissue-removing catheter for removing tissue ina body lumen, the tissue-removing catheter comprising: an elongate bodyhaving an axis and proximal and distal end portions spaced apart fromone another along the axis, the elongate body being sized and shaped tobe received in the body lumen; and a tissue-removing element mounted onthe distal end portion of the elongate body, the tissue-removing elementcomprising a body including an exterior surface having a first segmentextending from a proximal end toward a distal end of the tissue-removingelement, a second segment extending from the first segment toward thedistal end of the tissue-removing element, and a third segment extendingfrom the second segment to the distal end of the tissue-removingelement, a transition between the first and second segments defining afirst angle formed between the first and second segments, and atransition between the second and third segments defining a second angleformed between the second and third segments, the tissue-removingelement being configured to remove the tissue as the tissue-removingelement is rotated by the elongate body within the body lumen.
 2. Atissue-removing catheter as set forth in claim 1, wherein thetissue-removing element has a longitudinal axis, the first segmenthaving a cross-sectional dimension extending perpendicular to thelongitudinal axis of the tissue-removing element that increases from theproximal end of the tissue-removing element to the second segment.
 3. Atissue-removing catheter as set forth in claim 2, wherein the secondsegment has a cross-section dimension extending perpendicular to thelongitudinal axis of the tissue removing element that remains constantfrom the first segment to the third segment.
 4. A tissue-removingcatheter as set forth in claim 3, wherein the third segment has across-sectional dimension extending perpendicular to the longitudinalaxis of the tissue-removing element that decreases from the secondsegment to the distal end of the tissue-removing element.
 5. Atissue-removing catheter as set forth in claim 1, further comprising acavity extending through the body of the tissue-removing element fromthe proximal end to the distal end.
 6. A tissue-removing catheter as setforth in claim 5, wherein the cavity includes a first section extendingdistally from the proximal end of the tissue-removing element and asecond section extending proximally from the distal end of thetissue-removing element, the first section having a largercross-sectional dimension than a cross-sectional dimension of the secondsection.
 7. A tissue-removing catheter as set forth in claim 6, whereinthe cavity includes a third section extending from the first section tothe second section, the third section having a cross-sectional dimensionthat decreases from the first section to the second section.
 8. Atissue-removing catheter as set forth in claim 6, wherein thecross-sectional dimension of the first section is about 0.035 inches(0.9 mm).
 9. A tissue-removing catheter as set forth in claim 6, whereinthe cross-sectional dimension of the second section is about 0.022inches (0.56 mm).
 10. A tissue-removing catheter as set forth in claim1, wherein the distal end of the tissue-removing element is blunt.
 11. Atissue-removing catheter as set forth in claim 1, wherein the body ofthe tissue-removing element comprises one of stainless steel, titanium,brass, and ceramic.
 12. A tissue-removing catheter as set forth in claim11, wherein the exterior surface of the body comprises a diamond gritcoating.
 13. A tissue-removing catheter as set forth in claim 12,wherein the diamond grit coating comprises between about 2 and about 50μm of exposed diamond crystals.
 14. A tissue-removing catheter as setforth in claim 1, wherein the tissue-removing element is radiopaqueconfiguring the tissue-removing element to be visible under fluoroscopy.15. A tissue-removing element for use with a tissue removing catheterfor removing tissue in a body lumen, the tissue-removing elementcomprising a body including an exterior surface having a first segmentextending from a proximal end toward a distal end of the tissue-removingelement, a second segment extending from the first segment toward thedistal end of the tissue-removing element, and a third segment extendingfrom the second segment to the distal end of the tissue-removingelement, a transition between the first and second segments defining afirst angle formed between the first and second segments, and atransition between the second and third segments defining a second angleformed between the second and third segments, the tissue-removingelement being configured to remove the tissue as the tissue-removingelement is rotated by the tissue-removing catheter within the bodylumen.
 16. A tissue-removing element as set forth in claim 15, whereinthe tissue-removing element has a longitudinal axis, the first segmenthaving a cross-sectional dimension extending perpendicular to thelongitudinal axis of the tissue-removing element that increases from theproximal end of the tissue-removing element to the second segment.
 17. Atissue-removing element as set forth in claim 15, wherein the secondsegment has a cross-section dimension extending perpendicular to thelongitudinal axis of the tissue removing element that remains constantfrom the first segment to the third segment.
 18. A tissue-removingelement as set forth in claim 15, wherein the third segment has across-sectional dimension extending perpendicular to the longitudinalaxis of the tissue-removing element that decreases from the secondsegment to the distal end of the tissue-removing element.
 19. Atissue-removing element as set forth in claim 15, further comprising acavity extending through the body of the tissue-removing element fromthe proximal end to the distal end, wherein the cavity includes a firstsection extending distally from the proximal end of the tissue-removingelement, a second section extending proximally from the distal end ofthe tissue-removing element, and a third section extending from thefirst section to the second section, the first section having a largercross-sectional dimension than a cross-sectional dimension of the secondsection, and the third section having a cross-sectional dimension thatdecreases from the first section to the second section.
 20. Atissue-removing element of claim 15, wherein the distal end of thetissue-removing element is blunt.